Emerald is a precious stone of the beryl variety like sapphire, ruby and diamond. Emerald is coloured green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Emerald is a cyclosilicate.

Emerald is the birthstone of May and is the traditional gift for the 20th, 35th and 55th wedding anniversary in the US. These pieces are set in sterling silver.